66640829 has 2 divisors, whose sum is σ = 66640830. Its totient is φ = 66640828.

The previous prime is 66640807. The next prime is 66640831. The reversal of 66640829 is 92804666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65205625 + 1435204 = 8075^2 + 1198^2 .

It is a cyclic number.

It is not a de Polignac number, because 66640829 - 2¹² = 66636733 is a prime.

Together with 66640831, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66640859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33320414 + 33320415.

It is an arithmetic number, because the mean of its divisors is an integer number (33320415).

Almost surely, 2^66640829 is an apocalyptic number.

It is an amenable number.

66640829 is a deficient number, since it is larger than the sum of its proper divisors (1).

66640829 is an equidigital number, since it uses as much as digits as its factorization.

66640829 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 66640829 is about 8163.3834284566. The cubic root of 66640829 is about 405.4277429669.

The spelling of 66640829 in words is "sixty-six million, six hundred forty thousand, eight hundred twenty-nine".